1. Field of the Invention
The present invention is directed to a miniature pushbutton switch utilizing a coil spring as a movable contact for contact closing.
2. Description of the Prior Art
Japanese Laid-Open Publication No. 6-60755 discloses two types miniature pushbutton switches utilizing a torsion coil spring of electrically conductive material as a movable contact for contact closing. One type of the switches utilizes a coil spring having first and second arms extending from a coil portion of the coil spring. The coil spring is disposed with the first arm held in a constant electrical engagement with a first contact and with the second arm held in an engageable relation to a second contact. A pushbutton is connected to move the second arm into direct engagement with the second contact. With this configuration of directly displacing the second arm or applying a force of moving the second arm against the bias of the coil spring in order to make the electrical connection between the second arm and the second contact, the switch is difficult to give a sufficient contacting pressure at the very beginning of engaging the arm to the contact, which reduces reliable switching operation.
The other type of the switches is proposed to develop a desired contacting pressure by the use of an axially elongated coil spring. The coil spring is arranged to have one axial end thereof in a contact electrical engagement with a first contact and the other axial end in an engageable relation with a second contact. The pushbutton is connected to resiliently deform the coil spring along the axial length thereof for making the electrical connections with the second contact, thereby connecting the first and second contacts through the coil spring. Since this switch makes the use of the resilient deformation of the coil spring along the length thereof and therefore requires the coil spring of a relatively long axial length for contact closing, it is difficult to make the switch compact particularly with regard to a dimension between the first and second contacts.